To insert value from text field into MySQL database

I am trying to insert a value that user inputs from applet's text field into MySQL database. The connection is made and it does input when I put some string in, but I have to call the variable which contains the inputted string from text field.

I'm having one more problem: when I input string the database inputs many rows with the same content in that field where I inputted string and only ID changes. I'm working in NetBeans.

Here is my action method where I defined the action with text field (plaintext is my textfield and plaintextvalue is the label which displays inputed value in text field on applet...):